As acknowledged by the SESAR program, current ATC systems must be drastically improved to accommodate the predicted traffic growth in Europe. In this context, the Episode 3 project aims at assessing the performance of new ATM concepts, like 4D-trajectory planning and strategic deconfliction. Building on a preliminary ground holding algorithm aimed at directly solving all conflicts (instead of satisfying sector capacity constraints), a prior flight level allocation program is used to reduce the complexity of the traffic input, dramatically improving the quality of the solutions. We present Constraint Programming (CP) models of these large scale combinatorial optimization problems and the encouraging results obtained with the FaCiLe constraint library. However, our approach does not yet address uncertainties and we plan to overcome this issue by improving the robustness of our conflict model and iteratively solving the problem over a sliding time window.
